Flexible metallic tubing.



H. TIDEMAN.

FLEXIBLE METALLIC TUBING.

APPLICATION FILED JUNE 24, 1910.

973,238. Patented Oct. 18,1910.

UNITED STATES PATENT omen.

lunar rmanan, or mnnoxmn'rz, uranium, ass'renon or onn-mmr r0 auras worn, or cmcaeo, ILLmors.

FLEXIBLE mama roams.

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the following is a full, clear,'and precise specification.

My invention relates to flexible 'metallic tubing or conduit adapted particularly in the electric art for receiving electrical conductors or in other arts for conducting fluids and gases.

My invention concerns particularly that class of ubing which comprises outer and inner spiral members where the coils of the other member overla stices between the co' s of the inner member.

One of the salient objects ofmy invention is to provide improved stock havlng a crosssection which will enable the stock. to be more readily handled and wound to form the inner and outer spirals of the tubing, the cross-sections of the stock forthe inner and outer coils being such that they can be very readily drawn or rolled.

Another salient object is to provide a form of stock for the inner spiral member which will present a smooth and straight inner surface so that when the stock is wound into spiral form with thecoils close together the tubing will have a substantially. cylindrical inner surface which will not chafe wires or conductors drawn through the tubing and which will offer the least resistance to the flow of gases or fluids.

Another salient object is to providean outer surface of the stock for the inner coil and an inner surface of the stock for the outer coil, which surfaces will cooperate when the coils are formed to lock the inner coils together and to form a tight connection between the inner'coils, which connection, however, is yieldi enough to allow the tubing to be readily fiient, the arrangement bein also such that the greater the bend of t e tubing the greater will be the pressure between the outer and inner coils and the tighter will be the sealing connection between the-inner coils. Thls feature eliminates the necessity of pacldngbetween the coils to prevent leakage when gases and fluids under pressure are conducted through the tubing.

The nature of my invention will be readily and bridge the 'inter- -When this stock iswound into sistanoe to the p gases or cent inner coils, therl understood by reference to the following specification and the accompanying drawand in section to more clearly illustrate the construction and arrangement and showing also a finish thimble arranged atone end of the tubing, and Fig, 2 is a similar view showing the arrangement when the tubing is bent.

The tubi comprises outer and inner spirals 1 an 2 of which the-cross-sectimis are clearly indicated. The stock for the spirals can be readily rolled or drawn out like wire, the stock for the inner member havingl a straight, unbroken inner surface 3 and aving ong its outside edges the triangular ridges 4 and 5 forming between them 1 the tria ar median groove 6. spiral form the contiguous straight inner surfaces of the coils form a smooth, cylindrical inner surface for the tubing which offers the least re tors throu h. th onto the flow of 1h uidesai The MM for the outer spira as a m an cen triangularr1 7 and the flanges 8 and 9 along the ou edge, triangular grooves or channels 10 and 11 being formed between. the central ridge 7 and these edge '11 The outer surface of therstock is roun ed to be tially semi cylindrical, as shown. After the inner spiral has been wound the outer spiral is wound about the periphery thereof, the grooves or channels 10 and 11 of the outer coils recei the ri 4 and 5 of adjal be 'I of thtf! fitmcm s engag tween 7 e ridges o 'acent inner t z di ls and the flanges 8 and 9 of the outer'coils en the outer surfaces of the ridges of adpacent inner coils. The apex angle of the central ridge of the outer member may be the same as the angles of the ridges on the inner member, or may be greater, as shown. the tubing is straight, as indicated in 1, the points of the ridges on the inner coils engage intimately in the apexes of the grooves 10 and Patented Oct. 18, 1910.

of electrical conduc agecoils. If the tubing is used for conducting fluids under pressure tllB-IPI'ESSLITQ will have a tendency to expand the inner coils more than the outer coils on account of the greater surface presented by the inner coils; and the result is that the greater the pressure the more intimately will the ridges on the inner coils be associated, with the grooves and surfaces of the outer coils. In other words, increase in pressure within the tubing results in increase of sealing connection between the inner coils, and the necessity for' additional packing or sealing material-= .i's, therefore, eliminated when the tubing is used for gases or fluids under pressure. ()wing to the cylindrical inner surface presented by the inner spiral, end or finish thimbles 12 can be readily inserted without the necessity of special tools or apparatus.

The inner surface 13 of the thimbles can be rounded and tapered inwardly, as shown, so

as to prevent chafing of conductors whens pulled through the tubing. This straight cylindrical inner surface of the tubing also enables tubing sections to be very readily coupled together with a tight fit.

If the tubing is designed to be bent, the inner spiral is wound to leave gaps 14 between the coils, so thatwhen the tubing is bent the sections of the inner coils along the concave side of the bend will approach each other and the ends of the coils adjacent the convex side of the behd will separate, as indicated in Fi 2. Upon such bending the outer coils expand and the ends of the flanges 4 and 5 will leave the grooves or,

channels 10 and 11, the points of the flanges 4 and 5 along the concave side of the bend being brought more intimately into engagement with the faces of the central ridge 7 and the inner faces of the rid being pressed more intimately into engagement with the fla 8 and 9. Eflicient scaling between the coils will, therefore, in no way be diminished upon bending of the tubing, the sea efliciency being in fact greater at the hen lVhen wires are drawn through tubing the greatest chafing will of course occur where the wires are drawn along bends. In my tubing, however, the surface over. which the wires pass when d rawu about a bend is smooth and contiguous and practiallly cylindrical, owing to the fact that the inner coils along the concave side of the bend engage to hrin ther'the. inner surfaces at this point, tliis forming the unbroken, substantially cylindrical surface 15 acros which the wires drawn through the tubing can pass with the least friction. I, therefore, provide flexible tubing which can be very efliciently used for :m-onuuodating electrical or other conduc tors for gases and fluids, and which presents a cylindrical inner surface which oifers the least. resistance to the drawing through of ges 4 and 5 tudinal trian wires or to the flow of gases and fluids, and

1. In flexible tubing, the combination of an elastic metallic band vhaving an exterior triangular ridgeadjacenlzeach longitudinal edge and wound into s iral forin to form the interior member 0 the tubing, and a metallic band of elastic material having triangular grooves on its inner surface adjacent its lon 'tudina-l edges and wound spirally about t e inner member and spanning adjacent coils of the inner member with its grooves receiving the triangular ridges of adjacent coils of the inner member to flexibly lock said inner coils together.

2. In flexible tubing, the combination of an elastic metallic band having an exterior triangular ridge adjacent each longitudinal edge and wound into spiral form to form the interior member of the tubing, and a metallic'band of elastic material having trianlar grooves on its innersurfaceadjacent its longitudinal edges and wound spirally about the inner member and spanning adjacent coils of the inner member with its grooves receiving the triangular ridges of andarrangemen t which adjacent coils of the inner member to flexibly 1 look said inner coils together, the inner surface of the band for the inner member being lanar whereby when said band is wound into spiral form to form a substantially cylindrical interior surface for the tubing.

3. In flexible metallic tubing, the combination of an inner spiral member having exterior triangular longitudinal ridges, and an outer spiral member having interior longilar grooves for receiving said triangular ri es to flexibly lock the coils of the inner mem r together.

4. In flexible'metallic tubing, the'combination of an inner spiral member having ex terior triangular lon 'tudinal ridges, and an outer spiral member avin interior longitudinal triangular grooves or receiving said triangular ridges to flexibly lock the coils of the inner member together, the inner surfaces of the'coils of theinner member forming a substantially'continuous cylindrical inner surface for the tubing.

5. In flexible tubing, the combination of an inner spiral memberformed of an elastic metallic band having two triangular longitudinal ridges on its outer side, and'an exterior spiral member formed of an elastic metallic band having two longitudinal triangular grooves on its inner side intimately receiving triangular ridges of adjacent coils of the inner spiral member.

6. In flexible tubing, the combination of an inner spiral member formed of an elastic metallic band having two triangular longitudinal ridges on its outer side, and an exterior spiral member formed of an elastic metallic band having two longitudinal triangular grooves on its inner side intimately receiving triangular rid es of adjacent coils of the inner spiral mem er, the inner surface of the band for the-inner member being straight and the coils thereof being wound close together whereby a substantially unbroken cylindrical inner surface is formed for the tubing.

7. In flexible tubing, the combination of an inner spiral member formed of an elastic metallic bar having two triangular ridges on its outer side, and an outer spiral member formed from an elastic metallic bar having an inner triangular ridge on its inner side and two outer ridges on its inner side adja cent said inner ridge, such ridges forming between them triangular grooves, said grooves intimately receiving the triangular ridges of adjacent coils of the inner member and said triangular ridge of the outer member engaging between the triangular ridges of adjacent coils of the inner member.

In witness hereof, I hereunto subscribe my name this day of March, A. D. 1910.

HENRY TIDEMAN. 

